Electroluminescence display device

ABSTRACT

Embodiments disclosed herein relate to an electroluminescence display device including a first electrode, a second electrode facing the first electrode, an emission layer between the first electrode and the second electrode, and a bank layer defining the emission layer. The bank layer may be disposed between the first electrode and the second electrode. The bank layer may include a first bank layer and a second bank layer. The second bank layer may include a black pigment. The first bank layer may be closer to the first electrode than the second bank layer, and the first bank layer may have a lower permittivity than the second bank layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/608,734 filed on May 30, 2017, which claims the priority ofRepublic of Korea Patent Application No. 10-2016-0079398 filed on Jun.24, 2016, Republic of Korea Patent Application No. 10-2016-0094623 filedon Jul. 26, 2016 and Republic of Korea Patent Application No.10-2016-0150348 filed on Nov. 11, 2016, with the Korean IntellectualProperty Office, all of which are incorporated herein by reference.

BACKGROUND Field

The present disclosure relates to an electroluminescence display deviceand more particularly, to an electroluminescence display device capableof reducing reflection of external light, reducing leakage current,improving an aperture ratio, and reducing an image quality defect causedby a light source for fingerprint recognition.

Description of the Related Art

Recently, the field of display for visually displaying electricalinformation signals has grown rapidly. Thus, various display devicesthat are thin and light weight, and have low power consumption have beendeveloped.

Specific examples of the display devices include a Liquid CrystalDisplay (LCD) device, a Plasma Display Panel (PDP) device, a FieldEmission Display (FED) device, an Electroluminescence Display Device,and the like.

An electroluminescence display device is a self-light emitting displaydevice. The electroluminescence display device uses anelectroluminescence element in which holes and electrons are injectedinto a light emitting layer from an electrode (anode) for injectingholes and an electrode (cathode) for injecting electrons, respectively,and the holes and electrons are combined into excitons. When theexcitons transition from an excited state to a ground state, light isemitted from the electroluminescence element.

The electroluminescence display device can be classified into a topemission type, a bottom emission type, a dual emission type, and thelike, depending on a direction of light emission, and can also beclassified into a passive matrix type, an active matrix type, and thelike, depending on a driving method.

The electroluminescence display device does not need a separate lightsource unlike an LCD device. Thus, the electroluminescence displaydevice can be manufactured into a thinner form with lighter weight thanthe LCD device. Further, the electroluminescence display device isadvantageous in terms of power consumption since it is driven with alower voltage than the LCD device. Also, the electroluminescence displaydevice has excellent color expression ability, a high response speed, awide viewing angle, and a high contrast ratio (CR). Therefore, theelectroluminescence display device has been researched as anext-generation display device.

SUMMARY

Embodiments disclosed herein relate to an electroluminescence displaydevice including a thin film transistor, a planarization layer on thethin film transistor, a first bank layer on a surface of theplanarization layer facing in a first direction, the thin filmtransistor disposed between the planarization layer and the first banklayer, the first bank layer having a higher refractive index than theplanarization layer, a second bank layer on a surface of the first banklayer facing in the first direction, the second bank layer having ahigher refractive index than the first bank layer, and a light emittinglayer between a first electrode on the planarization layer and a secondelectrode on the second bank layer.

In one or more embodiments, the second bank layer includes a blackpigment.

In one or more embodiments, the second bank layer includes more blackpigments than the first bank layer.

In one or more embodiments, a permittivity of the first bank layer isless than a permittivity of the second bank layer.

In one or more embodiments, a portion of the second bank layer has asmaller width along a second direction perpendicular to the firstdirection than another portion of the second bank layer. The portion ofthe second bank layer may be farther away from the first bank layer thansaid another portion of the second bank layer.

In one or more embodiments, the second bank layer is directly in contactwith the first bank layer.

In one or more embodiments, the first bank layer has a thickness D,D=(2m+1)λ/4, λ being a wavelength of light incident on the planarizationlayer in the first direction, λ being 700 nm or more, m being an integernot less than zero. The first bank layer may be configured to absorb aportion of the light corresponding to a wavelength of 700 nm or less.

In one or more embodiments, the electroluminescence display devicefurther includes a spacer on a surface of the second bank layer facingin the first direction. The spacer may include a black pigment.

Embodiments disclosed herein relate to an electroluminescence displaydevice including a first electrode, a second electrode facing the firstelectrode, an emission layer between the first electrode and the secondelectrode, and a bank layer defining the emission layer. The bank layermay be disposed between the first electrode and the second electrode.The bank layer may include a first bank layer and a second bank layer.The second bank layer may include a black pigment. The first bank layermay be closer to the first electrode than the second bank layer, and thefirst bank layer may have a lower permittivity than the second banklayer.

In one or more embodiments, the first bank layer includes the blackpigment.

In one or more embodiments, the second bank layer has more blackpigments than the first bank layer.

In one or more embodiments, the second bank layer has a higherrefractive index than the first bank layer.

In one or more embodiments, the electroluminescence display devicefurther includes a spacer on a surface of the bank layer away from thefirst electrode. The spacer may be formed of a transparent material orincluding the black pigment.

Embodiments disclosed herein relate to an electroluminescence displaydevice comprising a thin film transistor on a surface of a substratefacing in a first direction, a planarization layer on the surface of thesubstrate, the planarization layer covering the thin film transistor,the thin film transistor disposed between the planarization layer andthe substrate, the planarization layer having a first area having afirst thickness along the first direction and a second area having asecond thickness along the first direction, the first thickness smallerthan the second thickness, a first electrode on the first area of theplanarization layer, the first electrode electrically connected to thethin film transistor, a bank layer on a portion of the second area ofthe planarization layer, the bank layer including a black pigment, anemission structure including a transport layer and a light emittinglayer on a surface of the first electrode facing in the first direction,and a second electrode on a surface of the emission structure facing inthe first direction.

In one or more embodiments, at least a part of the first electrode ispositioned on an inclined surface of the planarization layer. Theinclined surface may be disposed between the first area and the secondarea of the planarization layer. The inclined surface of theplanarization layer may face in a slanted direction from the firstdirection.

In one or more embodiments, an optical density of the bank layer is 4 orless.

The effects of the present disclosure are not limited to theaforementioned effects, and other effects, which are not mentionedabove, will be apparent to a person having ordinary skill in the artfrom the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view of an electroluminescence displaydevice according to an exemplary embodiment of the present disclosure;

FIG. 2 is a cross-sectional view of an emission structure of anelectroluminescence display device according to an exemplary embodimentof the present disclosure;

FIG. 3 is a diagram illustrating a method of measuring a reflectionluminance of an electroluminescence display device according to anexemplary embodiment of the present disclosure;

FIG. 4 is a cross-sectional view of an electroluminescence displaydevice according to another exemplary embodiment of the presentdisclosure;

FIG. 5A and FIG. 5B are diagrams provided to explain a method ofmanufacturing an electroluminescence display device according to anotherexemplary embodiment of the present disclosure;

FIG. 6A and FIG. 6B are diagrams provided to explain a method ofmanufacturing an electroluminescence display device according to yetanother exemplary embodiment of the present disclosure;

FIG. 7 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure;

FIG. 8 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure;

FIG. 9A through FIG. 9E are diagrams provided to explain a method ofmanufacturing an electroluminescence display device according to stillanother exemplary embodiment of the present disclosure;

FIG. 10 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure;

FIG. 11 is a diagram illustrating a light transmittance of a first banklayer in an electroluminescence display device in each wavelength bandaccording to still another exemplary embodiment of the presentdisclosure;

FIG. 12 is a cross-sectional view of an area A of FIG. 10; and

FIG. 13 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Advantages and features of the present disclosure, and methods foraccomplishing the same will be more clearly understood from exemplaryembodiments described below with reference to the accompanying drawings.However, the present disclosure is not limited to the followingexemplary embodiments but maybe implemented in various different forms.The exemplary embodiments are provided only to complete disclosure ofthe present disclosure and to fully provide a person having ordinaryskill in the art to which the present disclosure pertains with thecategory of the disclosure.

The shapes, sizes, ratios, angles, numbers, and the like illustrated inthe accompanying drawings for describing the exemplary embodiments ofthe present disclosure are merely examples, and the present disclosureis not limited thereto. Like reference numerals generally denote likeelements throughout the present specification. Further, in the followingdescription, a detailed explanation of known related technologies may beomitted to avoid unnecessarily obscuring the subject matter of thepresent disclosure. The terms such as “including” and “having” usedherein are generally intended to allow other components to be addedunless the terms are used with the term “only”. Any references tosingular may include plural unless expressly stated otherwise.

Components are interpreted to include an ordinary error range even ifnot expressly stated.

When the position relation between two parts is described using theterms such as “on”, “above”, “below”, and “next”, one or more partsmaybe positioned between the two parts unless the terms are used withthe term “immediately” or “directly”.

When an element or layer is referred to as being “on” another element orlayer, it maybe directly on the other element or layer, or interveningelements or layers may be present.

Although the terms “first”, “second”, and the like are used fordescribing various components, these components are not confined bythese terms. These terms are merely used for distinguishing onecomponent from the other components. Therefore, a first component to bementioned below may be a second component in a technical concept of thepresent disclosure.

Throughout the whole specification, the same reference numerals denotethe same elements.

Since the size and thickness of each component illustrated in thedrawings are represented for convenience in explanation, the presentdisclosure is not necessarily limited to the illustrated size andthickness of each component.

The features of various embodiments of the present disclosure can bepartially or entirely bonded to or combined with each other and can beinterlocked and operated in technically various ways as can be fullyunderstood by a person having ordinary skill in the art, and theembodiments can be carried out independently of or in association witheach other.

Hereinafter, various exemplary embodiments of the present disclosurewill be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of an electroluminescence displaydevice according to an exemplary embodiment of the present disclosure.

Referring to FIG. 1, an electroluminescence display device 100 accordingto an exemplary embodiment of the present disclosure includes asubstrate 110, a thin film transistor 120 positioned on the substrate110, and an emission structure 150. The emission structure 150 ispositioned between a first electrode 140 and a second electrode 160 andincludes a plurality of transport layer and light emitting layers EML.

The electroluminescence display device 100 includes a plurality ofsub-pixels. A sub-pixel refers to an area of a minimum unit for actuallyemitting light. Further, a plurality of sub-pixels may form a minimumgroup that can express a white light. For example, three sub-pixels mayform a group, and a red sub-pixel, a green sub-pixel, and a bluesub-pixel may form a group. Otherwise, four sub-pixels may form a group,and a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a whitesub-pixel may form a group. However, the present disclosure is notlimited thereto. It is possible to design sub-pixels in various ways.FIG. 1 illustrates only one sub-pixel from among the plurality ofsub-pixels of the electroluminescence display device 100 for conveniencein explanation.

The substrate 110 of the electroluminescence display device 100according to an exemplary embodiment of the present disclosure isconfigured to support various components of the electroluminescencedisplay device 100 and formed of an insulating material. For example,the substrate 110 may be formed of glass or may be formed as a flexiblesubstrate using a flexible material such as polyethylene terephthalate(PET), polyethylene naphthalate (PEN), and polyimide. Further, if theelectroluminescence display device which can be easily implemented intoa flexible form is applied to an automotive lighting or an automotivedisplay, various designs and the degree of freedom in design of theautomotive lighting can be secured so as to be suitable for a structureor external appearance of a vehicle.

A buffer layer 131 configured to block penetration of impurities fromthe substrate 110 or the outside and protect various components of theelectroluminescence display device 100 may be formed on the substrate110. The buffer layer 131 may have a single layer or multiple layerstructure including, for example, a silicon oxide film (SiOx) or asilicon nitride film (SiNx), but is not limited thereto. The bufferlayer 131 may be omitted depending on a structure or characteristics ofthe electroluminescence display device 100.

The thin film transistor 120 including a semiconductor layer 122, a gateelectrode 121, a source electrode 123, and a drain electrode 124 isformed on the buffer layer 131.

Specifically, the semiconductor layer 122 is formed on the substrate110. A gate insulation layer 132 configured to insulate thesemiconductor layer 122 from the gate electrode 121 is formed on thesemiconductor layer 122. An interlayer insulation layer 133 configuredto insulate the gate electrode 121 from the source electrode 123 and thedrain electrode 124 is formed on the gate electrode 121. The sourceelectrode 123 and the drain electrode 124 each of which is in contactwith the semiconductor layer 122 are formed on the interlayer insulationlayer 133. The source electrode 123 or the drain electrode 124 iselectrically connected to the semiconductor layer 122 through a contacthole.

The semiconductor layer 122 may be formed of amorphous silicon (a-Si),polycrystalline silicon (poly-Si), oxide semiconductor, organicsemiconductor, or the like. If the semiconductor layer 122 is formed ofoxide semiconductor, it may be formed of any one of indium gallium zincoxide (IGZO), zinc tin oxide (ZTO), indium zinc oxide (IZO), or indiumtin zinc oxide (ITZO), but is not limited thereto.

The gate insulation layer 132 may have a single layer or multiple layerstructure formed of an inorganic insulating material such as a siliconoxide film (SiO), and a silicon nitride film (SiNx), but is not limitedthereto.

The gate electrode 121 functions to transfer a gate signal to the thinfilm transistor 120, and may be formed of at least one of metals such asaluminum (Al), molybdenum (Mo), titanium (Ti), and copper (Cu) or alloysthereof. The gate electrode 121 may have a single layer or multiplelayer structure formed of the metals or alloys thereof, but is notlimited thereto.

The source electrode 123 and the drain electrode 124 function totransfer an electrical signal transferred from the outside to theemission structure 150 via the thin film transistor 120. The sourceelectrode 123 and the drain electrode 124 may be formed of at least oneof metals such as aluminum (Al), molybdenum (Mo), titanium (Ti), andcopper (Cu) or alloys thereof. The source electrode 123 and the drainelectrode 124 may have a single layer or multiple layer structure formedof the metals or alloys thereof, but are not limited thereto.

In the present disclosure, the driving thin film transistor 120electrically connected to the first electrode 140 from among variousthin film transistors which can be included in the electroluminescencedisplay device 100 has been illustrated for convenience in explanation.Each sub-pixel may further include a switching thin film transistor or acapacitor.

A passivation layer 170 is formed on the thin film transistor 120. Thepassivation layer 170 may be formed of an inorganic insulating material.For example, the passivation layer 170 may be formed of a silicon oxidefilm (SiOx), a silicon nitride film (SiNx), or the like, but is notlimited thereto. The passivation layer 170 may be omitted on a structureor characteristics of the electroluminescence display device 100.

A planarization layer 134 is formed on the passivation layer 170. Theplanarization layer 134 functions to flatten components such as the thinfilm transistor 120 on the substrate 110. The planarization layer 134maybe configured as a single layer or a plurality of layers, and may beformed of an organic material. For example, the planarization layer 134may be formed of polyimide, photo acryl, or benzocyclobutene (BCB), butis not limited thereto.

The passivation layer 170 and the planarization layer 134 include acontact hole 135 for electrically connecting the thin film transistor120 and the first electrode 140 in each sub-pixel.

The first electrode 140 is formed on the planarization layer 134. Thefirst electrode 140 may be an anode and may be formed of a conductivematerial having a relatively high work function value. Thus, the firstelectrode 140 functions to supply holes to a transport layer of theemission structure 150. The first electrode 140 is electricallyconnected to the thin film transistor 120 through the contact hole 135formed in the passivation layer 170 and the planarization layer 134. Forexample, the first electrode 140 may be electrically connected to thesource electrode 123 of the thin film transistor 120. Further, the firstelectrodes 140 of different subpixels are spaced apart from each other.The first electrode 140 is formed of a transparent conductive material,and may be formed of, for example, indium tin oxide (ITO), indium zincoxide (IZO), and the like, but is not limited thereto.

If the electroluminescence display device 100 according to an exemplaryembodiment of the present disclosure is of a top-emission type, lightemitted from the light emitting layer of the emission structure 150 isreflected by the first electrode 140. In this case, a reflective layerformed of a metal material, for example, aluminum (Al) or silver (Ag),having a high reflection efficiency may be further formed on an upper orlower part of the first electrode 140 in order for the light to be morereadily released in an upward direction.

For example, the first electrode 140 may have a two-layer structure inwhich a transparent conductive layer formed of a transparent conductivematerial and a reflective layer are laminated in sequence. Otherwise,the first electrode 140 may have a three-layer structure in which atransparent conductive layer, a reflective layer, and a transparentconductive layer are laminated in sequence. The reflective layer may beformed of silver (Ag) or an alloy including silver. For example, thereflective layer may be formed of silver (Ag) or APC (Ag/Pd/Cu).

In the electroluminescence display device 100 according to an exemplaryembodiment of the present disclosure, the top-emission type refers to astructure in which light emitted from the light emitting layer of theemission structure 150 is output in a direction toward the secondelectrode 160. A bottom-emission type refers to a structure in which thelight is output in a direction toward the first electrode 140 on thecontrary to the top-emission type.

The emission structure 150 is formed on the first electrode 140, a firstbank layer 141, and a second bank layer 142. The emission structure 150may include various transport layers as necessary, and essentiallyincludes the light emitting layer EML. The light emitting layer mayinclude an organic material, but is not limited thereto. Further, theemission structure 150 may include a plurality of light emitting layersdepending on a structure of the electroluminescence display device. Thetransport layers may include at least one hole transport layer HTL andone electron transport layer ETL, and may further include functionallayers such as a hole injection layer HIL, an electron injection layerEIL, a hole blocking layer HBL, and an electron blocking layer EBL.Further, the plurality of transport layers included in the emissionstructure 150 may have a common layer structure so as to correspond to ared sub-pixel R, a green sub-pixel G, and a blue sub-pixel B.

The second electrode 160 is formed on the emission structure 150. Thesecond electrode 160 may be a cathode and supply electrons to the lightemitting layer of the emission structure. Thus, the second electrode 160is formed of a conductive material having a low work function. Morespecifically, the second electrode 160 may be formed of a metal materialsuch as magnesium (Mg), and silver-magnesium (Ag:Mg), but is not limitedthereto.

If the electroluminescence display device 100 according to an exemplaryembodiment of the present disclosure is of the top-emission type, thesecond electrode 160 may be formed of transparent conductive oxide suchas indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zincoxide (ITZO), zinc oxide (ZnO), and tin oxide (TiO), but is not limitedthereto.

FIG. 2 is a cross-sectional view of an emission structure of anelectroluminescence display device according to an exemplary embodimentof the present disclosure.

Hereinafter, the emission structure 150 of the electroluminescencedisplay device 100 according to an exemplary embodiment of the presentdisclosure will be described in more detail with reference to FIG. 2.

Referring to FIG. 2, the emission structure 150 of theelectroluminescence display device 100 according to an exemplaryembodiment of the present disclosure includes a hole injection layer(HIL) 151, a first hole transport layer (1st HTL) 152 a on the HIL 151,a second hole transport layer (2nd HTL) 152 b and a third hole transportlayer (3rd HTL) on the 1st HTL 152 a, an organic light emitting layerEML including a red light emitting layer 153 a, a green light emittinglayer 153 b, and a blue light emitting layer 153 c disposed on the HTLs152 a, 152 b, and 152 c, and an electron transport layer (ETL) 154 onthe EML.

The first electrode 140 is disposed on the planarization layer 134 so asto correspond to each of a red sub-pixel area R, a green sub-pixel areaG, and a blue sub-pixel area B defined on the substrate.

The HIL 151 is disposed on the first electrode 140 as a common layercorresponding to the red sub-pixel area R, the green sub-pixel area G,and the blue sub-pixel area B.

The HIL 151 may function to facilitate injection of holes, and may beformed of at least one of HATCN(1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (copperphthalocyanine), PEDOT(poly(3,4)-ethylenedioxythiophene), PANI(polyaniline) and NPD(N,N-dinaphthyl-N,N′-diphenylbenzidine),TPD(N,N′-Bis(3-methylphenyl)-N,N″-bis(phenyl)-benzidine),α-NPB(Bis[N-(1-naphthyl)-N-phenyl]benzidine),TDAPB(1,3,5-tris(4-diphenylaminophenyl)benzene),TCTA(Tris(4-carbazoyl-9-yl)triphenylamine),spiro-TAD(2,2′,7,7″-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene) andCBP(4,4′-bis(carbazol-9-yl)biphenyl), but is not limited thereto.

The HIL 151 may be formed by doping a material of the 1st HTL 152 a witha p-dopant. In this case, the HIL 151 and the 2nd HTL 152 b can beformed in a single processing device through a continuous process. Thep-dopant may be formed of F₄-TCNQ(2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinidimethane), but is notlimited thereto.

The 1st HTL 152 a is disposed on the HIL 151 as a common layercorresponding to the red sub-pixel area R, the green sub-pixel area G,and the blue sub-pixel area B. The 1st HTL 152 a functions to facilitatetransport of holes, and may be formed of any one or more ofNPD(N,N-dinaphthyl-N,N′-diphenylbenzidine),TPD(N,N′-bis-(3-methylphenyl)-N,N′-bis-(phenyl)-benzidine),spiro-TAD(2,2′,7,7″-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene) andMTDATA(4,4′,4″-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine),but is not limited thereto.

The 2nd HTL 152 b is disposed on the 1st HTL 152a in the red sub-pixelarea R. Further, the 3rd HTL 152 c is disposed on the 1st HTL 152 a inthe green sub-pixel area G.

The 2nd HTL 152 b and the 3rd HTL 152 c function to facilitate transportof holes from the HIL 151 to the red light emitting layer 153 a and thegreen light emitting layer 153 b, respectively.

Further, a thickness of each of the 2nd HTL 152 b and the 3rd HTL 152 cmay form an optical distance of micro cavity. More specifically, thethickness of each of the 2nd HTL 152 b and the 3rd HTL 152 c may bedetermined such that the red light emitting layer 153 a forms a microcavity structure between the first electrode 140 and the secondelectrode 160 and the green light emitting layer 153 b forms a microcavity structure between the first electrode 140 and the secondelectrode 160. The optical distance of the micro cavity is formed in thered sub-pixel area R and the green sub-pixel area G, so that theefficiency of the electroluminescence display device 100 can beimproved.

The red light emitting layer 153 a is disposed on the 2nd HTL 152 b inthe red sub-pixel area R. The red light emitting layer 153 a may includea light emitting material that emits a red light. The light emittingmaterial may be formed using a phosphorescent material or a fluorescentmaterial.

More specifically, the red light emitting layer 153 a may include a hostmaterial including CBP (carbazole biphenyl) or mCP(1,3-bis(carbazol-9-yl)benzene), and may be formed of a phosphorescentmaterial including any one or more dopants from among

Ir(btp)₂(acac) (bis(2-benzo[b]thiophen-2-yl-pyridine) (acetylacetonate)iridium(III)), Ir(piq)₂(acac) (bis(1-phenylisoquinoline)(acetylacetonate)iridium(III)),Ir(piq)₃(tris(1-phenylquinoline)iridium(III)), andPtOEP(octaethylporphyrin platinum). Otherwise, the red light emittinglayer 153 a may be formed of a fluorescent material includingPBD:Eu(DBM)3(Phen) or perylene, but is not limited thereto.

The green light emitting layer 153 b is disposed on the 3rd HTL 152 c inthe green sub-pixel area G. The green light emitting layer 153 b mayinclude a light emitting material that emits a green light. The lightemitting material maybe formed using a phosphorescent material or afluorescent material.

More specifically, the green light emitting layer 153 b may include ahost material including CBP or mCP, and may be formed of aphosphorescent material including a dopant material such as an iridium(Ir) complex including

Ir(ppy)₃(tris(2-phenylpyridine)iridium(III)) or Ir(ppy)₂(acaa)(bis(2-phenylpyridine) (acetylacetonate)iridium(III). Otherwise, thegreen light emitting layer 153 b may be formed of a fluorescent materialincluding

Alq₃(tris(8-hydroxyquinolino) aluminum), but is not limited thereto.

The blue light emitting layer 153 c is disposed on the 1st HTL 152 a inthe blue sub-pixel area B. The blue light emitting layer 153 c mayinclude a light emitting material that emits a blue light. The lightemitting material may be formed using a phosphorescent material or afluorescent material.

More specifically, the blue light emitting layer 153 c may include ahost material including CBP or mCP, and may be formed of aphosphorescent material including a dopant material including

FIrPic(bis(3,5,-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III)).Further, the blue light emitting layer 153 c may be formed of afluorescent material including any one ofDPVBi(4,4′-bis[4-di-p-tolylamino)styryl)biphenyl),DSA(1-4-di-[4-(N,N-di-phenyl)amino]styryl-benzene), aPFO(polyfluorene)-based polymer, a PPV(polyphenylenevinylene)-basedpolymer, but is not limited thereto.

The ETL 154 is disposed on each of the red light emitting layer 153 a,the green light emitting layer 153 b, and the blue light emitting layer153 c so as to correspond to the red sub-pixel area R, the greensub-pixel area G, and the blue sub-pixel area B.

The ETL 154 may function to transport and inject electrons. A thicknessof the ETL 154 may be adjusted considering electron transportproperties.

The ETL 154 functions to facilitate transport of electrons, and may beformed of any one or more of Liq(8-hydroxyquinolinolato-lithium),Alq₃(tris (8-hydroxyquinolinato) aluminum),PBD(2-(4-biphenylyl)-5-(4-tert-butylpheny)-1,3,4oxadiazole),TAZ(3-(4-biphenyl)4-phenyl-5-tert-butylphenyl-1,2,4-triazole),spiro-PBD, and BAlq(bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminum), but is not limited thereto.

Further, an electron injection layer (EIL) can be further provided onthe ETL 154.

The EIL may be formed of an inorganic metal compound such as BaF₂, LiF,NaCl, CsF, Li₂O, and BaO, but is not limited thereto.

Herein, the structure is not limited according to an exemplaryembodiment of the present discourse. At least any one of the HIL 151,the 1st HTL 152 a, the 2nd HTL 152 b, the 3rd HTL 153 c, and the ETL 154may be omitted. Further, any one of the HIL 151, the 1st HTL 152 a, the2nd HTL 152 b, the 3rd HTL 153 c, and the ETL 154 may be formed as twoor more layers.

The second electrode 160 is disposed on the ETL 154 so as to correspondto the red sub-pixel area R, the green sub-pixel area G, and the bluesub-pixel area B.

A capping layer may be disposed on the second electrode 160. The cappinglayer functions to improve the light extraction effect of theelectroluminescence display device. The capping layer may be formed ofany one of host materials of the 1st HTL 152 a, the ETL 154, the redlight emitting layer 153 a, the green light emitting layer 153 b, andthe blue light emitting layer 153 c. Further, the capping layer may beomitted depending on a structure or characteristics of theelectroluminescence display device 100.

The EML 153 of the electroluminescence display device 100 according toan exemplary embodiment of the present disclosure maybe formed includingat least one phosphorescent material. More specifically, the EML 153 mayinclude the red light emitting layer 153 a for emitting a red light inthe red sub-pixel R, the green light emitting layer 153 b for emitting agreen light in the green sub-pixel G, and the blue light emitting layer153 c for emitting a blue light in the blue sub-pixel B. In this case,the red light emitting layer 153 a may include a phosphorescent materialand the green light emitting layer 153 b and the blue light emittinglayer 153 c may include a fluorescent material. Otherwise, the red lightemitting layer 153 a and the green light emitting layer 153 b mayinclude a phosphorescent material and the blue light emitting layer 153c may include a fluorescent material. Alternatively, the red lightemitting layer 153 a, the green light emitting layer 153 b, and the bluelight emitting layer 153 c may include a phosphorescent material.

Further, the electroluminescence display device 100 according to anexemplary embodiment of the present disclosure may be applied to variousdisplay devices including a TV, a mobile, a tablet PC, a monitor, alaptop computer, an automotive display, and an automotive lighting.Further, the electroluminescence display device 100 may also be appliedto a wearable display device, a foldable display device, a bendabledisplay device, a rollable display device, and the like.

FIG. 3 is a diagram illustrating a method of measuring a reflectionluminance of an electroluminescence display device according to anexemplary embodiment of the present disclosure.

In one example, a reflection luminance is measured by the luminance oflight reflected at a reflection angle of 30 degrees from among manyreflected beams of light Y when light of 400 Knit (an incident lightdenoted as “X” in FIG. 2) is incident into the electroluminescencedisplay device 100 at an angle of 45 degrees. The reflection luminancemaybe measured using a DMS803. The reflection luminance of theelectroluminescence display device 100 illustrated in FIG. 1 wasmeasured using this apparatus, and will be described as an example. Thereflection luminance is 300 nit or more at a reflection angle of 30degrees when light of 400 Knit is incident at an incident angle of 45degrees. If the reflection luminance is 300 nit or more, a visualsensitivity in the left and right directions of the electroluminescencedisplay device 100 may be decreased due to reflection of external light.Therefore, in order to reduce reflection of the external light by theelectroluminescence display device 100, the bank layers 141 and 142 maybe formed of a material that does not reflect light incident from theoutside.

In one aspect, the bank layers include a black pigment in order toreduce reflection of external light. However, if the bank layers areformed of the material including the black pigment, an optical density(OD) may increase. If the OD is increased, a permittivity of the banklayers is increased, which may cause leakage current of theelectroluminescence display device. Advantageously, anelectroluminescence display device disclosed herein can reduce leakagecurrent even when the OD is increased and also reduce reflection ofexternal light.

Referring to FIG. 1 again, the bank layers 141 and 142 can define thesub-pixels and may include at least two layers. That is, the first banklayer 141 may be more adjacent to the first electrode 140 than a secondbank layer 142, and the second bank layer 142 may be more adjacent tothe second electrode 160 than the first bank layer 141. Further, thefirst bank layer 141 and the second bank layer 142 expose a part of anupper surface of the first electrode 140. Specifically, as illustratedin FIG. 3, the first bank layer 141 and the second bank layer 142 may bedisposed to cover an edge of the first electrode 140.

Further, the first bank layer 141 may have a greater width than thesecond bank layer 142 in order to secure a margin caused by theformation of the second bank layer 142 of an organic material. In otherwords, an open portion of the second bank layer 142 may have a greaterwidth than an open portion of the first bank layer 141, but is notlimited thereto.

The second bank layer 142 may be formed by a photolithography process.That is, a photoresist maybe formed on the first electrode 140 to formthe bank layers 141 and 142 and then, the second bank layer 142 may beformed by the photolithography process.

The photoresist refers to a photosensitive resin which is changed insolubility to a developer by action of light and thus makes it possibleto obtain a pattern. The photoresist can be classified into a positivephotoresist and a negative photoresist. With the positive photoresist, alight exposure part is increased in solubility to a developer and thenthe light exposure part is removed during a developing process, so thata pattern can be obtained. Further, with the negative photoresist, alight exposure part is decreased in solubility to a developer and then anon-light exposure part is removed during a developing process, so thata pattern can be obtained.

In order to reduce reflection of external light by theelectroluminescence display device 100, the second bank layer 142 isformed of a material that reduces reflection of external light.Therefore, a photoresist for forming the second bank layer 142 mayinclude a black pigment. The black pigment may be formed of an organicmaterial or an inorganic material. Further, the black pigment may beformed of a carbon-based material, metal oxide, or the like. Further,the photoresist may include photosensitive compounds including at leastone of a polymer, a monomer, and a photoinitiator. Furthermore, thephotoresist may include a solvent that disperses the photosensitivecompounds.

According to reaction mechanism, the black pigment in the photoresist isdispersed in the photosensitive compounds by the solvent beforeexposure. The solvent of the photoresist can be removed by a vacuumdrying process or a curing process. Further, the photoinitiator includedin the photosensitive compounds generates radicals by light afterexposure. Then, the monomer included in the photoresist has a doublebond and thus reacts with the radicals of the photoinitiator so as toform cross-linking. Therefore, the photoresist has a high molecularweight after exposure and thus is not dissolved by the developer. Then,during a subsequent developing process using the developer, a part whichis not dissolved by the developer becomes the second bank layer 142 anda part which is dissolved by the developer is removed. Therefore, thephotoresist included in the second bank layer 142 may be referred to asa negative photoresist.

Further, the photoinitiator included in the photoresist may include animine-based photoinitiator to improve cross-linking after exposure. Forexample, the imine-based photoinitiator may include at least one ofoxime and oxime ester.

In this case, oxime or oxime ester is a photoinitiator having a longwavelength and capable of improving cross-linking. Herein, the longwavelength refers to 365 nm or more. Further, a light source used forexposure is a high-pressure mercury lamp having various wavelengths. Thevarious wavelengths may include G-line of 436 nm, H-line of 405 nm, andI-line of 365 nm. Particularly, the I-line of 365 nm or more is used toperform a photolithography process.

Further, oxime or oxime ester can reduce the generation of a by-productof exposure. Therefore, in a baking process as a subsequent process ofthe cross-linking, impurities caused by a reaction between theby-product and other molecules can be reduced. Further, oxime or oximeester is used together with the black pigment. Therefore, the secondbank layer 142 having a high light-shielding property can be formed.Otherwise, acetophenone may be further included in the photoinitiator inaddition to oxime or oxime ester.

For example, oxime may be represented by the following Chemical Formula1.

Herein, R and R′ may be one of an alkyl group or a phenyl group having 1to 15 carbon atoms.

For example, oxime ester may be represented by the following ChemicalFormula 2.

Herein, R may be an aryl group and R′ may be one of an alkyl group or aphenyl group having 1 to 15 carbon atoms.

The monomer may include 6 functional groups, and may include, forexample, dipentaerythritol hexaacrylate (DPHA). Herein, DPHA has adouble bond and can be quickly cured by light after the cross-linking.Therefore, the photoresist for forming the second bank layer 142 may beformed as a solid film with an improved anti-developing property. Thus,even in a developing process using a high-concentration developer, thefilm may not be lost.

Further, the polymer in the photoresist includes a cardo-based polymer.The cardo-based polymer has an excellent heat resistance and miscibilitywith a pigment and also has an excellent solubility. Also, the polymerin the photoresist may further include epoxy acrylate. Therefore, thepolymer in the photoresist including the cardo-based polymer or epoxyacrylate functions to disperse the black pigment in the polymer and thusimproves the dispersibility. The dispersibility refers to uniformity ofthe photoresist. As the dispersibility is increased, the second banklayer 142 can be formed in a uniform manner.

For example, the cardo-based polymer may be represented by the followingChemical Formula 3.

Further, the developer may be, for example, TMAH(tetramethylammoniumhydroxide) or KOH (potassium hydroxide).

Furthermore, since the second bank layer 142 includes the black pigment,an optical density which is the degree of shielding of light may beincreased. As the optical density is increased, reflection of externallight can be reduced. However, if the optical density is increased, apermittivity is increased, so that leakage current may be generated.

The leakage current refers to current flowing to an unintended sub-pixeladjacent to a target sub-pixel through a transport layer such as thehole injection layer or the hole transport layer, when another currentis applied to drive the target sub-pixel. Since the unintended sub-pixelemits light, the leakage current causes color mixing of light outputfrom two adjacent sub-pixels and causes a decrease in luminance.

Therefore, the first bank layer 141 is formed of a material with a lowpermittivity in order to reduce a permittivity of the second bank layer142 and to reduce the leakage current. That is, the bank layers 141 and142 may include at least two layers. Further, the first bank layer 141maybe more adjacent to the first electrode 140 than the second banklayer 142, and the second bank layer 142 may be more adjacent to thesecond electrode 160 than the first bank layer 141. Therefore, the firstbank layer 141 adjacent to the first electrode 140 may be formed of amaterial with a permittivity of 7 C/m² (Coulomb/m²) or less, and may beformed of an organic material or an inorganic material. For example, thefirst bank layer 141 maybe formed of one of polyimide, silicon oxide(SiOx), and silicon nitride (SiNx), but is not limited thereto.

Therefore, the first bank layer 141 adjacent to the first electrode 140is formed of a material with a lower permittivity than the second banklayer 142 adjacent to the second electrode 160. Thus, an optical densityof the second bank layer is increased due to the black pigment includedin the second bank layer 142. Therefore, even if a permittivity isincreased due to the second bank layer including the black pigment, thetotal permittivity of the first bank layer 141 and the second bank layer142 may be decreased. That is, the first bank layer 141 can reduceleakage current caused by an increase in permittivity of the second banklayer 142 and also suppress color mixing or a decrease in luminancebetween sub-pixels due to the leakage current.

Since the second bank layer 142 is formed of a material including theblack pigment, when an incident angle of an incident light is 45degrees, a reflection luminance at a reflection angle of 30 degrees maybe set to 30 nit or less. Therefore, reflection of external light can beimproved and the reflection luminance can be decreased. A reflectionluminance of the second bank layer 142 may be measured using a DMS803.Herein, the reflection luminance may include reflection luminance on theleft and right of the electroluminescence display device 100. That is,when an incident angle of an incident light is 45 degrees, the left andright reflection luminance may be 30 nit or less at a reflection angleof 30 degrees. Further, if the electroluminescence display device 100 isapplied to an automotive display, a display device with reducedreflection of external light can be provided. Furthermore, sincereflection of external light can be reduced by the electroluminescencedisplay device 100, a visual sensitivity, for example, in the left andright directions of the electroluminescence display device 100 can beimproved.

Therefore, the first bank layer 141 is formed of a material with a lowpermittivity and the second bank layer 142 is formed of a materialincluding the black pigment. Thus, it is possible to provide theelectroluminescence display device 100 in which the bank layer has animproved optical density with reduced leakage current. That is, it ispossible to provide the electroluminescence display device 100 in whichleakage current can be reduced by the first bank layer 141 andreflection of external light can be minimized by the second bank layer142.

The first bank layer 141 may be formed of the same material as thesecond bank layer 142. That is, the first bank layer 141 may be formedof the same material as the second bank layer 142 but a weight % (wt %)of a black pigment included in each of the first bank layer 141 and thesecond bank layer 142 may be different from each other. Therefore, aweight % (wt %) of a black pigment included in the first bank layer 141may be set to be smaller than that of a black pigment included in secondbank layer 142 so as to suppress an increase in permittivity. Forexample, the amount of a black pigment included in the first bank layer141 may be set to about 20 weight % (wt o) or less and the amount of ablack pigment included in the second bank layer 142 may be set to about40 weight % (wt %) or less, but are not limited thereto. In this case,the amount of a black pigment may be a weight % (wt %) of a blackpigment with respect to 100 weight % (wt o) of a photoresist for formingthe first bank layer 141 or the second bank layer 142. Further, apermittivity of the first bank layer 141 may be 7 C/m² or less and apermittivity of the second bank layer 142 may be 10 C/m² or less.

Therefore, even if the first bank layer 141 and the second bank layer142 are formed of the same material, the total permittivity of the firstbank layer 141 and the second bank layer 142 can be reduced by adjustinga weight % (wt %) of the black pigment. That is, it is possible toreduce leakage current caused by an increase in permittivity and alsopossible to suppress color mixing or a decrease in luminance of lightoutput from adjacent sub-pixels due to the leakage current.

FIG. 4 is a cross-sectional view of an electroluminescence displaydevice according to another exemplary embodiment of the presentdisclosure.

In explaining an electroluminescence display device 200 according toanother exemplary embodiment of the present disclosure, detaileddescription of components identical or corresponding to those of theabove-described exemplary embodiment will be omitted or brieflyprovided.

A spacer 246 may suppress a defect caused by a contact with a mask whena plurality of transport layers or light emitting layers EML is formedon the emission structure 150 or the second electrode 160 is formed onthe emission structure 150.

The spacer 246 is disposed on a partial area of the second bank layer142 adjacent to the second electrode 160, and may be formed on an areaother than sub-pixels of the electroluminescence display device 200.That is, the spacer 246 may be disposed on a non-pixel area. Thenon-pixel area maybe an area other than an emission area. The spacer 246may be formed of one of polyimide, photo acryl, and benzocyclobutene(BCB) which are transparent materials.

Even if the second bank layer 142 is formed of a material including theblack pigment, reflection of external light by the second bank layer 142may be reduced, since the spacer 246 formed of a transparent materialcauses scattering of light. Further, if the second bank layer 142 andthe spacer 246 are respectively formed of different materials, aphotolithography process maybe performed two times. Thus, the number ofprocesses may be increased.

Therefore, the spacer 246 may be formed of the same material as thesecond bank layer 142 in order to reduce reflection and scattering ofexternal light and scattering and simplify the manufacturing process ofthe electroluminescence display device 200. A photoresist for formingthe spacer 246 includes a black pigment. Further, the photoresist forforming the spacer 246 may include photosensitive compounds including atleast one of a polymer, a monomer, and a photoinitiator. The polymer inthe photoresist may include at least one of a cardo-based polymer andepoxy acrylate. Further, the monomer in the photoresist may include 6functional groups, and may include, for example, dipentaerythritolhexaacrylate (DPHA). Also, the photoinitiator in the photoresist mayinclude at least one of oxime and oxime ester, and may also include asolvent that disperses the photosensitive compounds.

Since the spacer 246 is formed of the same material as the second banklayer 142 and the second bank layer 142 and the spacer 246 can be formedby the same photolithography process, the manufacturing process can besimplified. That is, since the second bank layer 142 and the spacer 246can be formed by a halftone process using a halftone mask, themanufacturing process can be simplified. Details thereof will bedescribed below with reference to FIG. 5A and FIG. 5B.

FIG. 5A and FIG. 5B are diagrams provided to explain a method ofmanufacturing an electroluminescence display device according to anotherexemplary embodiment of the present disclosure.

As illustrated in FIG. 5A and FIG. 5B, a photoresist 290 including ablack pigment is formed on the first bank layer 141. The photoresist mayinclude photosensitive compounds including at least one of a polymer, amonomer, and a photoinitiator. Further, the photoresist may also includea solvent that disperses the photosensitive compounds. The polymer inthe photoresist may include at least one of a cardo-based polymer andepoxy acrylate. Further, the monomer in the photoresist may include 6functional groups, and may include, for example, dipentaerythritolhexaacrylate (DPHA). Also, the photoinitiator in the photoresist mayinclude one of oxime and oxime ester. Furthermore, the solvent of thephotoresist may be propylene glycol monomethyl ether acetate (PGMEA).

Before an exposure process, the solvent of the photoresist maybe removedby a vacuum drying process or a curing process. Then, a mask is disposedon the photoresist 290 and an exposure process which is aphotolithography process and a developing process are performed. Themask is a halftone mask with different light transmittances. That is,the mask includes a transflective region M1, a transmission region M2,and a shielding region M3. The photoresist 290 corresponding to thetransflective region M1 is formed as the second bank layer 142 in afirst area a. Further, the photoresist 290 corresponding to thetransmission region M2 is formed as the spacer 246 on the second banklayer 142 in a third area c. The shielding region M3 of the mask refersto a region that shields light, and exposes a part of the firstelectrode 140 and the first bank layer 141 in a second area b through adeveloping process. A width of an upper surface of the first bank layer141 may be greater than a width of a lower surface of the second banklayer 142, but is not limited thereto. Specifically, the photoresist inthe transflective region M1 and the transmission region M2 exposed tolight through the mask is converted into a polymer cross-linked by lightand thus does not react with a developer. The photoresist in theshielding region M3 which is not exposed to light is removed by reactionwith the developer. Therefore, the emission structure 150 may be formedin the second area b. After the developing process, a baking process(e.g., a heating process) may be performed to form the second bank layer142 and the spacer 246. That is, the second bank layer 142 may be formedand the spacer 246 may also be formed on the partial area of the secondbank layer 142 adjacent to the second electrode 160.

Further, as illustrated in FIG. 4, the emission structure 150 may beformed on a partial area of the first electrode 140, the second banklayer 142, and the spacer 246. Also, the second electrode 160 may beformed on the emission structure 150.

Further, since the second bank layer 142 and the spacer 246 include theblack pigment, light is absorbed during the exposure process. Therefore,it is difficult to apply the halftone process thereto. In order to solvethis problem, the amount of exposure maybe increased during the exposureprocess. For example, the amount of exposure may be in the range of from40 mJ to 100 mJ.

FIG. 6A and FIG. 6B are diagrams provided to explain a method ofmanufacturing an electroluminescence display device according to yetanother exemplary embodiment of the present disclosure.

FIG. 6A and FIG. 6B are diagrams provided to explain a process ofmanufacturing the first bank layer 141, the second bank layer 142, andthe spacer 246 by the same process such as the halftone process.Further, an electroluminescence display device manufactured asillustrated in FIG. 6A and FIG. 6B may have the same configuration asthe electroluminescence display device illustrated in FIG. 4. Therefore,an explanation thereof will be omitted.

As illustrated in FIG. 6A and FIG. 6B, a first photoresist 291 includinga black pigment is formed on the first electrode 140. A secondphotoresist 292 including a black pigment is formed on the firstphotoresist 291. The first photoresist 291 and the second photoresist292 may include photosensitive compounds including at least one of apolymer, a monomer, and a photoinitiator. Further, the first photoresist291 and the second photoresist 292 may also include a solvent thatdisperses the photosensitive compounds. The polymer in the firstphotoresist 291 and the second photoresist 292 may include at least oneof a cardo-based polymer and epoxy acrylate. Further, the monomer in thefirst photoresist 291 and the second photoresist 292 may include 6functional groups, and may include, for example, dipentaerythritolhexaacrylate (DPHA). Also, the photoinitiator in the first photoresist291 and the second photoresist 292 may include at least one of oxime andoxime ester. Furthermore, the solvent of the photoresist may bepropylene glycol monomethyl ether acetate (PGMEA).

Further, a weight % (wt %) of a black pigment included in each of thefirst photoresist 291 and the second photoresist 292 may be differentfrom each other. For example, the amount of a black pigment included inthe first photoresist 291 may be set to about 20 weight % (wt %) or lessand the amount of a black pigment included in the second photoresist 292maybe set to about 40 weight % (wt %) or less, but are not limitedthereto. In this case, the amount of a black pigment may be a weight %(wt %) of a black pigment with respect to 100 weight % (wt %) of thefirst photoresist 291 and the second photoresist 292.

Before an exposure process, the solvent of the first photoresist 291 andthe second photoresist 292 may be removed by a vacuum drying process ora curing process. Then, a mask is disposed on the first photoresist 291and the second photoresist 292 and an exposure process which is aphotolithography process and a developing process are performed. Themask is a halftone mask with different light transmittances. That is,the mask includes the transflective region M1, the transmission regionM2, and the shielding region M3. The first photoresist 291 and thesecond photoresist 292 corresponding to the transflective region M1 isformed as the first bank layer 141 and the second bank layer 142 in thefirst area a. Further, the second photoresist 292 corresponding to thetransmission region M2 is formed as the spacer 246 on the second banklayer 142 in the third area c. The shielding region M3 of the maskrefers to a region that shields light, and exposes the first electrode140 in the second area b through a developing process. A width of anupper surface of the first bank layer 141 may be the same as a width ofa lower surface of the second bank layer 142, but is not limitedthereto. Specifically, the photoresist in the transflective region M1and the transmission region M2 exposed to light through the mask isconverted into a polymer cross-linked by light and thus does not reactwith a developer. The photoresist in the shielding region M3 which isnot exposed to light is removed by reaction with the developer.Therefore, an emission structure may be formed in the second area b.After the developing process, a baking process, (e.g., a heatingprocess) may be performed to form the first bank layer 141, the secondbank layer 142, and the spacer 246. Therefore, the first bank layer 141,the second bank layer 142, and the spacer 246 can be formed by the sameprocess such as the halftone process. Thus, the manufacturing processcan be simplified.

Further, as illustrated in FIG. 4, the emission structure 150 may beformed on a part of the first electrode 140 and on the second bank layer142 and the spacer 246. Further, the second electrode 160 may be formedon the emission structure 150.

Furthermore, since the first bank layer 141, the second bank layer 142,and the spacer 246 include the black pigment, light is absorbed duringthe exposure process. Therefore, it is difficult to apply the halftoneprocess thereto. In order to solve this problem, the amount of exposuremay be increased during the exposure process. For example, the amount ofexposure may be in the range of from 40 mJ to 100 mJ.

FIG. 7 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure.

In explaining an electroluminescence display device 300 according tostill another exemplary embodiment of the present disclosure, detaileddescription of components identical or corresponding to those of theabove-described exemplary embodiments will be omitted or brieflyprovided.

A planarization layer 334 is formed on the passivation layer 170. Theplanarization layer 334 functions to flatten components such as the thinfilm transistor 120 on the substrate 110. That is, an upper surface ofthe planarization layer 334 formed on the thin film transistor 120 has aflatten surface. The planarization layer 334 may be configured as asingle layer or a plurality of layers, and may be formed of an organicmaterial. For example, the planarization layer 334 maybe formed ofpolyimide, photo acryl, or benzocyclobutene (BCB), but is not limitedthereto. The passivation layer 170 and the planarization layer 334include the contact hole 135 for electrically connecting the thin filmtransistor 120 and a first electrode 340 in each sub-pixel.

Further, referring to FIG. 7, the planarization layer 334 of theelectroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure may include a first areaR1 having a first thickness

A and a second area R2 having a second thickness B greater than thefirst thickness A. The first thickness A may be the thickness from anupper surface of the passivation layer 170 to a lower surface of thefirst electrode 340. Further, the second thickness B may be thethickness from the upper surface of the passivation layer 170 to a lowersurface of the second bank layer 142.

The electroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure includes an emission areaEA and a non-emission area NEA. The emission area EA corresponds to anarea where the first electrode 140 and the emission structure 150 are indirect contact with each other. The non-emission area NEA corresponds toan area where the first electrode 140 and the emission structure 150 areseparated by the first bank layer 141. The first area R1 of theplanarization layer 334 may be positioned corresponding to the emissionarea EA, and the second area R2 may be positioned corresponding to thenon-emission area NEA. More specifically, the planarization layer 334 isformed to have the first thickness A in the first area R1 and the secondthickness B greater than the first thickness A in the second area R2.Thus, the planarization layer 334 may be thicker in the non-emissionarea NEA than in the emission area EA.

Further, in the electroluminescence display device 300 according tostill another exemplary embodiment of the present disclosure, the firstarea R1 of the planarization layer 334 corresponding to the emissionarea EA is positioned between the second areas R2 of the planarizationlayer 334 corresponding to the non-emission areas NEA. Therefore, thesecond area R2 of the planarization layer 334 may function as a firstbank layer 334 b that defines the emission area EA of theelectroluminescence display device 300.

Further, the planarization layer 334 including the first area R1 havingthe first thickness A and the second area R2 having the second thicknessB greater than the first thickness A may be formed by the halftoneprocess using a halftone mask. The halftone mask includes a shieldingpart, a transmission part, and a transflective part. The shielding partrefers to a part that shields light. The transmission part refers to apart that transmits light. The transflective part refers to a part thattransmits a smaller amount of light than the transmission part. If thehalftone mask is used, different amount of light can be applied. Thus, apattern having different heights can be formed.

That is, the first bank layer 334 b included in the planarization layer334 may be formed of the same material on the same layer as a bottomplanarization layer 334 a. The first bank layer 334 b and the bottomplanarization layer 334 a may be formed by the same process using thehalftone mask. The first bank layer 334 b of the planarization layer 334may be formed of one of polyimide, photo acryl, or benzocyclobutene(BCB) in the same manner as the bottom planarization layer 334 a.

A permittivity of the first bank layer 334 b of the planarization layer334 in the electroluminescence display device 300 according to stillanother exemplary embodiment of the present disclosure may be determinedconsidering leakage current to an adjacent sub-pixel. The leakagecurrent refers to a current flowing to an unintended sub-pixel adjacentto a target sub-pixel through the common transport layer such as thehole injection layer or the hole transport layer, when another currentis applied to drive the target sub-pixel. Since the unintended sub-pixelemits light, the leakage current causes color mixing of light outputfrom adjacent sub-pixels and a decrease in luminance. To prevent leakagecurrent, the first bank layer 334 b of the planarization layer 334 inthe electroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure may be formed of amaterial with a low permittivity. Specifically, the first bank layer 334b may be formed of a material with a permittivity of, preferably, 7 C/m²(Coulomb/m²) or less.

The first electrode 340 is formed on the planarization layer 334. Thefirst electrode 340 may be an anode and may be formed of a conductivematerial having a relatively high work function value. Thus, the firstelectrode 340 functions to supply holes to a light emitting layer of theemission structure 150. The first electrode 340 is formed of atransparent conductive material, and may be formed of, for example,indium tin oxide (ITO), indium zinc oxide (IZO), and the like, but isnot limited thereto.

If the electroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure is of a top-emissiontype, light emitted from the light emitting layer of the emissionstructure 150 is reflected by the first electrode 340. In this case, areflective layer formed of a metal material, for example, aluminum (Al)or silver (Ag), having a high reflection efficiency may be furtherformed on an upper or lower part of the first electrode 340 in order forthe light to be projected in an upward direction through the secondelectrode 160.

For example, the first electrode 340 may have a two-layer structure inwhich a transparent conductive layer formed of a transparent conductivematerial and a reflective layer are laminated in sequence. Otherwise,the first electrode 340 may have a three-layer structure in which atransparent conductive layer, a reflective layer, and a transparentconductive layer are laminated in sequence. The reflective layer may beformed of silver (Ag) or an alloy including silver. For example, thereflective layer may be formed of silver (Ag) or APC (Ag/Pd/Cu).

Referring to FIG. 7, in the electroluminescence display device 300according to still another exemplary embodiment of the presentdisclosure, at least a part of the first electrode 340 may be positionedon an inclined surface of the first bank layer 334 b of theplanarization layer 334. In a comparative electroluminescence displaydevice, a first electrode is positioned under a bank layer. Thus, anemission area of the electroluminescence display device is limited to awidth of the first electrode exposed under the bank layer. Meanwhile, asdescribed above, at least a part of the first electrode 340 may bepositioned on the inclined surface of the first bank layer 334 b. Inthis case, a width of the first electrode 340 can be increased and awidth of the emission area EA of the electroluminescence display device300 is increased as compared with the comparative structure. Therefore,an aperture ratio of the electroluminescence display device 300 can beimproved. Further, the planarization layer 334 and the first bank layer334 b are formed by the same process, allowing a reduction in productioncost.

In the comparative electroluminescence display device, the bank layer isformed of a transparent material.

Therefore, light incident from the outside is transmitted by thetransparent bank layer and then reflected by the first electrode 340,and the like including a layer positioned under the bank layer andformed of a metal material. Therefore, in the electroluminescencedisplay device 300, reflection of external light may occur. Further, ifthe electroluminescence display device 300 is applied to an automotivedisplay, it is difficult to apply the electroluminescence display device300 to the automotive display due to reflection of external light. Toprevent reflection of external light by an electroluminescence displaydevice, the second bank layer 142 of the electroluminescence displaydevice 300 according to still another exemplary embodiment of thepresent disclosure maybe formed of a material that reduces reflection ofexternal light.

Referring to FIG. 7, in the electroluminescence display device 300according to still another exemplary embodiment of the presentdisclosure, the second bank layer 142 including the black pigment may bedisposed on the second area R2 of the planarization layer 334 having thesecond thickness B on the first bank layer 334 b. That is, thephotoresist for forming the second bank layer 142 may be a materialincluding the black pigment.

In the electroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure, the planarization layer334 on the thin film transistor includes the first area R1 having thefirst thickness A and the second area R2 having the second thickness Bgreater than the first thickness A. The second bank layer 142 formed ofa material including the black pigment is formed on the second area R2of the planarization layer 334. Thus, when an incident angle of lightincident into the electroluminescence display device 300 is 45 degrees,a reflection luminance at a reflection angle of 30 degrees may be set to30 nit or less. Thus, it is possible to reduce a surface reflectionluminance by reducing reflection of external light and thus possible toimprove field visibility of the electroluminescence display device ascompared with the comparative structure. Further, in theelectroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure, at least a part of thefirst electrode 340 is formed to be positioned on the inclined surfaceof the second area R2. Thus, the width of the emission area EA of theelectroluminescence display device 300 is increased. Therefore, anaperture ratio can be improved. Furthermore, in the electroluminescencedisplay device 300 according to still another exemplary embodiment ofthe present disclosure, the planarization layer 334 is formed as thefirst bank layer 334 b by the halftone process. Therefore, themanufacturing process of the electroluminescence display device 300 canbe simplified.

FIG. 8 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure.

In explaining an electroluminescence display device 400 according tostill another exemplary embodiment of the present disclosure, detaileddescription of components identical or corresponding to those of theabove-described exemplary embodiment will be omitted or brieflyprovided.

Referring to FIG. 8, the electroluminescence display device 400according to still another exemplary embodiment of the presentdisclosure may further include a spacer 446 on a partial area of thesecond bank layer 142. The spacer 446 may be formed of a transparentmaterial. The transparent material may be one of polyimide, photo acryl,and benzocyclobutene (BCB).

Further, in order to reduce reflection of external light, the spacer 446maybe formed including the black pigment in the same manner as thesecond bank layer 142. In this case, the second bank layer 142 and thespacer 446 may be formed by patterning through the same process such ashalftone process.

That is, if the spacer 446 is formed of the same material as the secondbank layer 142, the second bank layer 142 and the spacer 446 can beformed through the halftone process. Therefore, the manufacturingprocess of the electroluminescence display device 400 can be simplified.

That is, in the electroluminescence display device 400 according tostill another exemplary embodiment of the present disclosure, theplanarization layer 334 on the thin film transistor includes the firstarea R1 having the first thickness A and the second area R2 having thesecond thickness B greater than the first thickness A. The second banklayer 142 formed of a material including the black pigment is formed onthe second area R2 of the planarization layer 334 and the spacer 446 isformed on the second bank layer 142. Thus, it is possible to reduce asurface reflection luminance by reducing reflection of external lightand thus possible to improve field visibility of the electroluminescencedisplay device 400 as compared with the comparative structure.

Further, in the electroluminescence display device 400 according tostill another exemplary embodiment of the present disclosure, if thespacer 446 on the second bank layer 142 is formed of the same materialas the second bank layer 142, the second bank layer 142 and the spacer446 can be formed by the same process. Therefore, the manufacturingprocess of the electroluminescence display device 400 can be simplified.

FIG. 9A through FIG. 9E are diagrams provided to explain a method ofmanufacturing an electroluminescence display device according to stillanother exemplary embodiment of the present disclosure.

Referring to FIG. 9A, the buffer layer 131 is formed on the substrate110, and the thin film transistor 120 including the semiconductor layer122, the gate insulation layer 132, the gate electrode 121, theinterlayer insulation layer 133, the source electrode 123, and the drainelectrode 124 are formed on the buffer layer 131. Further, thepassivation layer 170 is formed on the thin film transistor 120.

Then, referring to FIG. 9B, the planarization layer 334 is formed on thepassivation layer 170. The planarization layer 334 may include the firstarea R1 having the first thickness A and the second area R2 having thesecond thickness B greater than the first thickness A.

More specifically, the first area R1 of the planarization layer 334 maybe formed to have the first thickness A and correspond to the emissionarea EA. The second area R2 of the planarization layer 334 may be formedto have the second thickness B greater than the first thickness A andcorrespond to the non-emission area NEA. That is, the planarizationlayer 334 maybe thicker in the non-emission area NEA than in theemission area EA. The second area R2 of the planarization layer 334 maybe the first bank layer 334 b of the electroluminescence display device300 according to still another exemplary embodiment of the presentdisclosure.

The planarization layer 334 including the first area R1 having the firstthickness A and the second area R2 having the second thickness B greaterthan the first thickness A may be formed by the halftone process usingthe halftone mask. That is, the first bank layer 334 b of theplanarization layer 334 may be formed of the same material on the samelayer as the bottom planarization layer 334 a. The first bank layer 334b of the planarization layer 334 and the bottom planarization layer 334a may be formed by patterning through the same process such as thehalftone process.

Then, referring to FIG. 9C, the first electrode 340 is formed on thebottom planarization layer 334 a of the planarization layer 334 and on apartial area of the first bank layer 334 b. The first electrode 340 iselectrically connected to the thin film transistor 120 of each of thesub-pixel through the contact hole 135 formed in the passivation layer170 and the planarization layer 334.

Further, at least a part of the first electrode 340 may be positioned onthe inclined surface of the first bank layer 334 b. As such, at least apart of the first electrode 340 may be positioned on the inclinedsurface of the first bank layer 334 b. In this case, a width of thefirst electrode 340 can be increased and a width of the emission area EAof the electroluminescence display device 300 is increased as comparedwith the comparative structure. Therefore, an aperture ratio of theelectroluminescence display device 300 can be improved.

Then, referring to FIG. 9D, the second bank layer 142 formed of amaterial including the black pigment is disposed on the second area R2of the planarization layer 334 having the second thickness B on thefirst bank layer 334 b. Since the second bank layer 142 is formed of amaterial including the black pigment, when an incident angle of anincident light is 45 degrees, a reflection luminance at a reflectionangle of 30 degrees may be set to 30 nit or less. Thus, it is possibleto reduce a reflection.

In order to stably form the bank layer having a multiple layerstructure, a lower end portion of the second bank layer 142 may have asmaller width than an upper end portion of the first bank layer 334 b ofthe planarization layer 334.

Then, referring to FIG. 9E, the emission structure 150 is formed on thefirst electrode 340, the first bank layer 334 b, and the second banklayer 142. The emission structure 150 may include various transportlayers as necessary and may also include a plurality of light emittinglayers. Further, the second electrode 160 is formed on the emissionstructure 150, so that the electroluminescence display device 300according to still another exemplary embodiment of the presentdisclosure can be manufactured.

That is, in the electroluminescence display device 300 according tostill another exemplary embodiment of the present disclosure, theplanarization layer 334 on the thin film transistor includes the firstarea R1 having the first thickness A and the second area R2 having thesecond thickness B greater than the first thickness A. The second banklayer 142 formed of a material including the black pigment is formed onthe second area R2 of the planarization layer 334. Thus, it is possibleto reduce a surface reflection luminance by reducing reflection ofexternal light and thus possible to improve field visibility of theelectroluminescence display device 300 as compared with the comparativestructure. Further, in the electroluminescence display device 300according to still another exemplary embodiment of the presentdisclosure, the bank layer includes the first bank layer 334 b formed ofthe same material on the same layer as the planarization layer 334 onthe thin film transistor 120 and the second bank layer 142 positioned onthe first bank layer 334 b and including the black pigment. Thus, anoptical density of the bank layer can be improved. Therefore, it ispossible to provide the electroluminescence display device 300 capableof reducing reflection of external light. Further, in theelectroluminescence display device 300 according to still anotherexemplary embodiment of the present disclosure, at least a part of thefirst electrode 340 is positioned on the inclined surface of the firstbank layer 334 b. Thus, a width of the emission area EA of theelectroluminescence display device 300 is increased. Thus, an apertureratio of the electroluminescence display device 300 can be improved.Furthermore, in the electroluminescence display device 300 according tostill another exemplary embodiment of the present disclosure, theplanarization layer 334 is formed as the first bank layer 334 b by thesame process such as the halftone process. Therefore, the manufacturingprocess of the electroluminescence display device 300 can be simplified.

FIG. 10 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure.

In explaining an electroluminescence display device 500 according tostill another exemplary embodiment of the present disclosure, detaileddescription of components identical or corresponding to those of theabove-described exemplary embodiment will be omitted or brieflyprovided.

The electroluminescence display device 500 according to still anotherexemplary embodiment of the present disclosure may include a lightsource 580 for fingerprint recognition positioned under the substrate110. The light source 580 may be further provided to theelectroluminescence display device 500 in order to implement opticalfingerprint recognition. Light irradiated from the light source 580 forfingerprint recognition toward the substrate 110 is reflected by auser's finger. Then, the reflected light is sensed by a photo sensorincluding the thin film transistor above the substrate 110, so that theuser's fingerprint is recognized.

In one or more embodiments, light having a short wavelength of 300 nm to700 nm or light having a long wavelength of 700 nm or more may beapplied by a light source 580 for fingerprint recognition in variousways depending on a structure of an electroluminescence display device.

Referring to FIG. 10, the electroluminescence display device 500according to still another exemplary embodiment of the presentdisclosure includes a first bank layer 541 covering at least a part ofthe first electrode 140 and formed on the planarization layer 134 and asecond bank layer 542 formed on the first bank layer 541.

Further, each of the first bank layer 541 and the second bank layer 542of the electroluminescence display device 500 according to still anotherexemplary embodiment of the present disclosure is formed including theblack pigment.

In the comparative electroluminescence display device, the bank layer isformed of a transparent material. Therefore, light incident from theoutside is transmitted by the transparent bank layer and then reflectedby the first electrode 140 including a layer positioned under the banklayer and formed of a metal material. Therefore, in theelectroluminescence display device 500, reflection of external light mayoccur. Further, if the electroluminescence display device 500 is appliedto an automotive display, it is difficult to apply theelectroluminescence display device 500 to the automotive display due toreflection of external light. In order to reduce reflection of externallight by an electroluminescence display device, the first bank layer 541and the second bank layer 542 of the electroluminescence display device500 according to still another exemplary embodiment of the presentdisclosure maybe formed of a material that reduces reflection ofexternal light.

Further, in order to perform fingerprint recognition, the first banklayer 541 and the second bank layer 542 may reduce transmission of lightoutput from under the substrate 110 such that light irradiated from thelight source 580 for fingerprint recognition under the substrate 110cannot be recognized by the user.

Referring to FIG. 10, each of the first bank layer 541 and the secondbank layer 542 of the electroluminescence display device 500 accordingto still another exemplary embodiment of the present disclosure maybeformed of a material including the black pigment. That is, a photoresistfor forming the first bank layer 541 and the second bank layer 542 maybe a material including the black pigment. The black pigment may beformed of an organic material or an inorganic material. In this case,the photoresist and the black pigment may be substantially the same asthe photoresist and the black pigment described above with reference toFIG. 1.

Further, since the first bank layer 541 and the second bank layer 542include the black pigment, an optical density which is the degree ofshielding of light may be increased. As the optical density isincreased, reflection of external light can be reduced. However, if theoptical density is excessively increased, a permittivity may beincreased, so that leakage current to an adjacent sub-pixel maybegenerated. In consideration of this matter, the first bank layer 541 andthe second bank layer 542 may have an optical density of, preferably, 4or less.

Further, since the first bank layer 541 and the second bank layer 542are formed of a material including the black pigment, when an incidentangle of an incident light incident is 45 degrees, a reflectionluminance at a reflection angle of 30 degrees may be set to 30 nit orless. Thus, it is possible to reduce a reflection luminance by improvingreflection of external light. That is, when an incident angle of anincident light is 45 degrees, the left and right reflection luminancemay be 30 nit or less at a reflection angle of 30 degrees. Further, ifthe electroluminescence display device 500 is applied to an automotivedisplay, a display device with reduced reflection of external light canbe provided. Furthermore, since reflection of external light can bereduced by the electroluminescence display device 500, a visualsensitivity, for example, in the left and right directions of theelectroluminescence display device 500 can be improved.

Also, the first bank layer 541 and the second bank layer 542 of theelectroluminescence display device 500 according to still anotherexemplary embodiment of the present disclosure are formed to havedifferent refractive indexes from each other. Further, the refractiveindexes of the first bank layer 541 and the second bank layer 542 aredifferent from a refractive index of the planarization layer 134.

More specifically, the first bank layer 541 may have a higher refractiveindex than the planarization layer 134 positioned under the first banklayer 541. For example, if a material having a refractive index of 1.49is applied as the planarization layer 134, a material having arefractive index of 1.55 may be applied as the first bank layer 541. Forexample, the first bank layer 541 may be formed of one of polyimide,photo acryl, and benzocyclobutene (BCB).

Further, the second bank layer 542 may have a higher refractive indexthan the first bank layer 541 positioned under the second bank layer542. For example, if a material having a refractive index of 1.55 isapplied as the first bank layer 541, a material having a refractiveindex of 1.60 may be applied as the second bank layer 542. For example,the second bank layer 542 having a higher refractive index than thefirst bank layer 541 may be formed including 4,4-thiodibenzenethiol(TDT)-based epoxy acrylate.

That is, in the electroluminescence display device 500 according tostill another exemplary embodiment of the present disclosure, therefractive index of the first bank layer 541 maybe set to be higher thanthat of the planarization layer 134. Further, the refractive index ofthe second bank layer 542 may be set to be higher than that of the firstbank layer 541.

While light output from the light source 580 for fingerprint recognitiondisposed under the substrate 110 passes through the planarization layer134, the first bank layer 541, and the second bank layer 542 havingdifferent refractive indexes from each other, a part of the light may bereflected toward the light source 580 for fingerprint recognition andthen shielded by the first bank layer 541 and the second bank layer 542.

That is, light output from the light source 580 for fingerprintrecognition disposed under the substrate 110 is reflected in part by aninterface between the planarization layer 134 and the first bank layer541 set to different refractive indexes from each other. Then, the lighttransmitted through the first bank layer 541 may be reflected in part byan interface between the first bank layer 541 and the second bank layer542 having different refractive indexes from each other.

Further, in the electroluminescence display device 500 according tostill another exemplary embodiment of the present disclosure, athickness of the first bank layer 541 may be set to satisfy D=(2m+1)λ/4when D is the thickness of the first bank layer 541, λ is a wavelengthof the light source 580 for fingerprint recognition having a wavelengthof 700 nm or more, and m is a positive integer or zero.

Therefore, if the thickness of the first bank layer 541 of theelectroluminescence display device 500 according to still anotherexemplary embodiment of the present disclosure is set to satisfyD=(2m+1)λ/4, a phase of the light reflected by the interface between theplanarization layer 134 and the first bank layer 541 is different180-degree from a phase of the light reflected by the interface betweenthe first bank layer 541 and the second bank layer 542. Light havingopposite phases are overlapped in wavelength with each other, resultingin destructive interference. Thus, the reflected light can bedissipated. Therefore, it is possible to reduce recognition of the lightoutput from the light source 580 for fingerprint recognition from theoutside.

Further, referring to FIG. 10, in order to stably form the second banklayer 542 on the first bank layer 541 having multiple layer structure, alower end portion of the second bank layer 542 may have a smaller widththan an upper end portion of the first bank layer 541.

Further, a permittivity of the first bank layer 541 of theelectroluminescence display device 500 according to still anotherexemplary embodiment of the present disclosure is determined accordingto leakage current to an adjacent sub-pixel. The leakage current refersto a current flowing to an unintended sub-pixel adjacent to a targetsub-pixel through the common transport layer such as the hole injectionlayer or the hole transport layer, when a current is applied to drivethe target sub-pixel. Since the unintended sub-pixel emits light, theleakage current causes color mixing of light output from adjacentsub-pixels and a decrease in luminance. Therefore, the first bank layer541 on the planarization layer 134 in the electroluminescence displaydevice 500 according to still another exemplary embodiment of thepresent disclosure may be formed of a material with a low permittivity.Specifically, the first bank layer 541 may be formed of a material witha permittivity of, preferably, 7 C/m² (Coulomb/m²) or less.

FIG. 11 is a diagram illustrating a light transmittance of a first banklayer in an electroluminescence display device in each wavelength bandaccording to still another exemplary embodiment of the presentdisclosure.

According to the result of evaluation of a light transmittance of thefirst bank layer 541 in the electroluminescence display device 500 ineach wavelength band with reference to FIG. 11, light is absorbed by thefirst bank layer 541 in a wavelength band of 300 nm to 700 nm. Thus,transmission of the light may not occur. However, in a wavelength bandof 700 nm or more, the light transmittance of the first bank layer 541may be sharply increased.

That is, if only the first bank layer 541 is applied to theelectroluminescence display device 500, when a light source forfingerprint recognition is disposed under the substrate, the first bank541 has a high light-shielding power with respect to a light sourcehaving a short wavelength of 300 nm to 700 nm but has a lowlight-shielding power with respect to a light source having a longwavelength of 700 nm or more. Therefore, light output from the lightsource 580 for fingerprint recognition under the substrate 110 cannot becompletely shielded by the bank layer, and may be recognized by theuser. Thus, a portion of a display may appear red causing degradation inimage quality.

FIG. 12 is a cross-sectional view of an area C of FIG. 10.

That is, FIG. 12 is a diagram provided to explain the conditions forlight absorption, reflection and destructive interference in the firstbank layer 541 and the second bank layer 542 of the electroluminescencedisplay device 500 according to still another exemplary embodiment ofthe present disclosure.

Referring to FIG. 12, the electroluminescence display device 500according to still another exemplary embodiment of the presentdisclosure includes the first bank layer 541 and the second bank layer542 positioned on the planarization layer 134 having differentrefractive indexes.

Referring to FIG. 12, if light output from a light source 180 forfingerprint recognition has a short wavelength band, e.g., between 300nm and 700 nm, as described above with reference to FIG. 11, the lightcan be absorbed and shielded by the first bank layer 541.

Further, referring to FIG. 12, the first bank layer 541 and the secondbank layer 542 of the electroluminescence display device 500 accordingto still another exemplary embodiment of the present disclosure areformed to have different refractive indexes from each other. In oneexample, a refractive index n1 of the planarization layer 134, arefractive index n2 of the first bank layer 541, and a refractive indexn3 of the second bank layer 542 may be n1<n2<n3.

The light source 180 for fingerprint recognition having a longwavelength of 700 nm or more may be applied to the electroluminescencedisplay device 500 according to still another exemplary embodiment ofthe present disclosure. In this case, if a refractive index of the firstbank layer 541 is set to be higher than that of the planarization layer134, light output from the light source 180 for fingerprint recognitionpositioned under the substrate 110 may be reflected in part toward thelight source 180 for fingerprint recognition by the interface betweenthe planarization layer 134 and the first bank layer 541 havingdifferent refractive indexes from each other.

Further, if a refractive index of the second bank layer 542 is set to behigher than that of the first bank layer 541, the light passing throughthe interface between the planarization layer 134 and the first banklayer 541 may also be reflected in part toward the light source 180 forfingerprint recognition by the interface between the first bank layer541 and the second bank layer 542 having different refractive indexesfrom each other.

That is, light output from the light source 180 for fingerprintrecognition positioned under the substrate 110 may be reflected in partby the interface between the planarization layer 134 and the first banklayer 541 having different refractive indexes from each other. Also, thelight passing through the first bank layer 541 may be reflected in partby the interface between the first bank layer 541 and the second banklayer 542 having different refractive indexes from each other.

Therefore, light output from the light source 180 for fingerprintrecognition positioned under the substrate 110 may be reflected in parttoward the light source 180 for fingerprint recognition while passingthrough the planarization layer 134, the first bank layer 541, and thesecond bank layer 542 having different refractive indexes from eachother. Thus, the light can be shielded by the first bank layer 541 andthe second bank layer 542.

Further, in the electroluminescence display device 500 according tostill another exemplary embodiment of the present disclosure, athickness of the first bank layer 541 may be set to satisfy D=(2m+1)λ/4when D is the thickness of the first bank layer 541, λ is a wavelengthof the light source 180 for fingerprint recognition having a wavelengthof 700 nm or more, and m is a positive integer or zero.

When light passes through mediums having different refractive indexesfrom each other, transmission and reflection occur at an interfacebetween the mediums having different refractive indexes from each other.As the light travels from the medium having a low refractive index tothe medium having a high refractive index, a phase of the wavelength maybe changed 180-degree.

Therefore, if the thickness of the first bank layer 541 of theelectroluminescence display device 500 according to still anotherexemplary embodiment of the present disclosure satisfies D=(2m+1)λ/4, aphase of the light reflected by the interface between the planarizationlayer 134 and the first bank layer 541 may be 180-degree offset from aphase of the light reflected by the interface between the first banklayer 541 and the second bank layer 542. The light having the oppositephases may cause destructive interference and be dissipated.

Therefore, light output from the light source 180 for fingerprintrecognition positioned under the substrate 110 may be reflected in parttoward the light source 180 for fingerprint recognition and thusshielded in part while passing through the planarization layer 134, thefirst bank layer 541, and the second bank layer 542 having differentrefractive indexes from each other. A thickness of the first bank layer541 may satisfy D=(2m+1)λ/4. Thus, the reflected light can be dissipatedby destructive interference. Therefore, reflection of light by the metallayer on the substrate can be reduced. Accordingly, an optical densityOD of the first bank layer 541 and the second bank layer 542 can beimproved and recognition of light by the user can be reduced.

That is, the electroluminescence display device 500 according to stillanother exemplary embodiment of the present disclosure includes thefirst bank layer 541 and the second bank layer 542 each formed of amaterial including the black pigment. The planarization layer 134, thefirst bank layer 541, and the second bank layer 542 have differentrefractive indexes from each other. Light output from the light source180 for fingerprint recognition under the substrate 110 is reflectedtoward the light source 180 for fingerprint recognition from under thefirst bank layer 541 and the second bank layer 542 due to a differencein refractive index. The first bank layer 541 has a specific thicknesssuitable for a wavelength of the light source. Thus, the light reflectedfrom under the first bank layer 541 and the second bank layer 542 may bedissipated by destructive interference. Therefore, the light output fromthe light source 180 for fingerprint recognition may not be recognizedby a user viewing the display device disclosed herein.

FIG. 13 is a cross-sectional view of an electroluminescence displaydevice according to still another exemplary embodiment of the presentdisclosure.

In explaining an electroluminescence display device 600 according tostill another exemplary embodiment of the present disclosure, detaileddescription of components identical or corresponding to those of theabove-described exemplary embodiment will be omitted or brieflyprovided.

Referring to FIG. 13, the electroluminescence display device 600according to still another exemplary embodiment of the presentdisclosure includes a spacer 646 formed on a partial area of the secondbank layer 542.

The spacer 646 may function to suppress a defect caused by a contactwith a mask, when a plurality of transport layers or light emittinglayers EML are deposited on the emission structure 150, or when thesecond electrode 160 is formed on the emission structure 150.

The spacer 646 may be formed of a transparent material. For example, thetransparent material may be anyone of polyimide, photo acryl, andbenzocyclobutene (BCB).

Further, the spacer 646 may be formed including the black pigment in thesame manner as the first bank layer 541 or the second bank layer 542.

Furthermore, if the spacer 646 is formed of the same material as thesecond bank layer 542 and includes the black pigment, the second banklayer 542 and the spacer 646 may be formed by the halftone process usingthe halftone mask. The halftone mask includes a shielding part, atransmission part, and a transflective part. The shielding part refersto a part that shields light. The transmission part refers to a partthat transmits light. The transflective part refers to a part thattransmits a smaller amount of light than the transmission part. If thehalftone mask is used, different amount of light can be applied. Thus, apattern having different heights can be formed through the same process.

The exemplary embodiments of the present disclosure can also bedescribed as follows:

Embodiments disclosed herein relate to an electroluminescence displaydevice including a thin film transistor, a planarization layer on thethin film transistor, a first bank layer on a surface of theplanarization layer facing in a first direction, the thin filmtransistor disposed between the planarization layer and the first banklayer, the first bank layer having a higher refractive index than theplanarization layer, a second bank layer on a surface of the first banklayer facing in the first direction, the second bank layer having ahigher refractive index than the first bank layer, and a light emittinglayer between a first electrode on the planarization layer and a secondelectrode on the second bank layer.

In one or more embodiments, the second bank layer includes a blackpigment.

In one or more embodiments, the second bank layer includes more blackpigments than the first bank layer.

In one or more embodiments, a permittivity of the first bank layer isless than a permittivity of the second bank layer.

In one or more embodiments, a portion of the second bank layer has asmaller width along a second direction perpendicular to the firstdirection than another portion of the second bank layer. The portion ofthe second bank layer maybe farther away from the first bank layer thansaid another portion of the second bank layer.

In one or more embodiments, the second bank layer is directly in contactwith the first bank layer.

In one or more embodiments, the first bank layer has a thickness D,D=(2m+1)λ/4, λ being a wavelength of light incident on the planarizationlayer in the first direction, λ being 700 nm or more, m being an integernot less than zero. The first bank layer may be configured to absorb aportion of the light corresponding to a wavelength of 700 nm or less.

In one or more embodiments, the electroluminescence display devicefurther includes a spacer on a surface of the second bank layer facingin the first direction. The spacer may include a black pigment.

Embodiments disclosed herein relate to an electroluminescence displaydevice including a first electrode, a second electrode facing the firstelectrode, an emission layer between the first electrode and the secondelectrode, and a bank layer defining the emission layer. The bank layermay be disposed between the first electrode and the second electrode.The bank layer may include a first bank layer and a second bank layer.The second bank layer may include a black pigment. The first bank layermay be closer to the first electrode than the second bank layer, and thefirst bank layer may have a lower permittivity than the second banklayer.

In one or more embodiments, the first bank layer includes the blackpigment.

In one or more embodiments, the second bank layer has more blackpigments than the first bank layer.

In one or more embodiments, the second bank layer has a higherrefractive index than the first bank layer.

In one or more embodiments, the electroluminescence display devicefurther includes a spacer on a surface of the bank layer away from thefirst electrode. The spacer may be formed of a transparent material orincluding the black pigment.

Embodiments disclosed herein relate to an electroluminescence displaydevice comprising a thin film transistor on a surface of a substratefacing in a first direction, a planarization layer on the surface of thesubstrate, the planarization layer covering the thin film transistor,the thin film transistor disposed between the planarization layer andthe substrate, the planarization layer having a first area having afirst thickness along the first direction and a second area having asecond thickness along the first direction, the first thickness smallerthan the second thickness, a first electrode on the first area of theplanarization layer, the first electrode electrically connected to thethin film transistor, a bank layer on a portion of the second area ofthe planarization layer, the bank layer including a black pigment, anemission structure including a transport layer and a light emittinglayer on a surface of the first electrode facing in the first direction,and a second electrode on a surface of the emission structure facing inthe first direction.

In one or more embodiments, at least a part of the first electrode ispositioned on an inclined surface of the planarization layer. Theinclined surface may be disposed between the first area and the secondarea of the planarization layer. The inclined surface of theplanarization layer may face in a slanted direction from the firstdirection.

In one or more embodiments, an optical density of the bank layer is 4 orless.

Although the exemplary embodiments of the present disclosure have beendescribed in detail with reference to the accompanying drawings, thepresent disclosure is not limited thereto and may be embodied in manydifferent forms without departing from the technical concept of thepresent disclosure. Therefore, the exemplary embodiments of the presentdisclosure are provided for illustrative purposes only but not intendedto limit the technical concept of the present disclosure. The scope ofthe technical concept of the present disclosure is not limited thereto.Therefore, it should be understood that the above-described exemplaryembodiments are illustrative in all aspects and do not limit the presentdisclosure. The protective scope of the present disclosure should beconstrued based on the following claims, and all the technical conceptsin the equivalent scope thereof should be construed as falling withinthe scope of the present disclosure.

What is claimed is:
 1. An electroluminescence display device comprising:a thin film transistor on a surface of a substrate facing in a firstdirection; a planarization layer on the surface of the substrate, theplanarization layer covering the thin film transistor, the thin filmtransistor disposed between the planarization layer and the substrate,the planarization layer having a first area having a first thicknessalong the first direction and a second area having a second thicknessalong the first direction, the first thickness smaller than the secondthickness; a first electrode on the first area of the planarizationlayer, the first electrode electrically connected to the thin filmtransistor; a bank layer on a portion of the second area of theplanarization layer, the bank layer including a black pigment; anemission structure including a transport layer and a light emittinglayer on a surface of the first electrode facing in the first direction;and a second electrode on a surface of the emission structure facing inthe first direction.
 2. The electroluminescence display device accordingto claim 1, wherein at least a part of the first electrode is positionedon an inclined surface of the planarization layer, the inclined surfacedisposed between the first area and the second area of the planarizationlayer.
 3. The electroluminescence display device according to claim 2,wherein the inclined surface of the planarization layer faces in aslanted direction from the first direction.
 4. The electroluminescencedisplay device according to claim 1, wherein an optical density of thebank layer is 4 or less.
 5. A display apparatus, comprising: a substrateincluding an upper surface and a lower surface; a thin film transistoron the upper surface of the substrate; a planarization layer coveringthe thin film transistor and the upper surface of the substrate, theplanarization layer including a first portion having a first thicknessand a second portion having a second thickness, the first thicknesssmaller than the second thickness; a first electrode on theplanarization layer, the first electrode being at the first portion ofthe planarization layer and electrically connected to the thin filmtransistor; a bank layer on the planarization layer, the bank layerbeing at the second portion of planarization layer and including a blackpigment; an emission structure on the first electrode, the emissionstructure including a transport layer and a light emitting layer; and ansecond electrode on the emission structure, the emission structurebetween the first electrode and the second electrode.
 6. The displayapparatus according to claim 5, wherein the first portion of theplanarization layer corresponds to an emission area where the firstelectrode and the emission structure are in direct contact with eachother.
 7. The display apparatus according to claim 6, wherein the firstportion of the planarization layer is overlapped with the emission area.8. The display apparatus according to claim 5, wherein the firstelectrode is spaced apart from the second portion of the planarizationlayer.
 9. The display apparatus according to claim 5, wherein the secondportion of the planarization layer includes an inclined surface, anupper surface, and a lower surface, the first portion of theplanarization layer includes an upper surface and a lower surface, theupper surface of the first portion is connected to the inclined surfaceof the second portion.
 10. The display apparatus according to claim 9,wherein both ends of the first electrode are on the inclined surface ofthe second portion of the planarization layer.
 11. The display apparatusaccording to claim 10, wherein the both ends of the first electrode areinterposed between the inclined surface of the second portion of theplanarization layer and the emission structure.